136. You have two database servers SEMP and SACCT. The database in the SEMP server maintains the
employee information and the database in the SACCT server maintains the accounts payable information.
The employees submit the expense reports to the accounts payable department. A user of the accounts
payable database wants to extract the employee information from the database in the SEMP server for
cross-verification.
Which schema object enables the user to access the information from the remote database?
A.Cluster
B.Database link
C.Mapping table
D.Materialized view
Answer: BWhat Are Database Links?
A database link is a pointer that defines a one-way communication path from an Oracle Database server to another database server. The link pointer is actually defined as an entry in a data dictionary table. To access the link, you must be connected to the local database that contains the data dictionary entry.
A database link connection is one-way in the sense that a client connected to local database A can use a link stored in database A to access information in remote database B, but users connected to database B cannot use the same link to access data in database A. If local users on database B want to access data on database A, then they must define a link that is stored in the data dictionary of database B.
A database link connection allows local users to access data on a remote database. For this connection to occur, each database in the distributed system must have a unique global database name in the network domain. The global database name uniquely identifies a database server in a distributed system.
